<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>边框</title>
    <style>
        .box{
            width:200px;
            height:200px;
            /*border:1px solid red;*/
            border-top:20px solid red;
            border-bottom: 20px double skyblue;
            border-right:20px dotted purple;
            border-left:20px dashed green;
        }
    </style>
</head>
<body>
    <div class="box"></div>
</body>
</html>